As the Delta-variant gradually takes over Malaysia, the Health Director-General, Dr Noor Hisham had stressed that the double masking and wearing face shields should be part of Malaysia’s strategy to curb the Covid-19 spread within the community.
Yesterday (23 August), Dr Noor Hisham had took to his Twitter to advise Malaysians to start practicing double masking by wearing a fabric mask on top of the medical procedure surgical mask together with a face shield as it will give us more protection against the Covid-19 Delta-variant virus.
In a series of tweet, he said “Face masks & face shields could help prevent community transmission when physical distancing & stay-at-home measures are relaxed or no longer possible.”
He then elaborated that these barriers, along with hand hygiene and avoid the practice of touching can help stop airborne respiratory droplets from reaching you.
In addition, he also mentioned that we need to adopt the practical use of face shields as part of our strategies to reduce transmission of Covid-19 in the community as it can be “quickly and affordably produced”.
Lastly, he added that studies had been conducted and they found that with the usage of a face shield with double masks, a 96% protection against the Delta variant could be achieved.
This is reaffirmed by a study that took place in 2014 by Lindsley et. al, where an experiment was conducted by using a coughing patient simulator and a breathing worker simulator.
Through that experiment, an influenza-laden cough aerosol with a volume median diameter (VMD) of 8.5 μm was used and the usage of only a face shield managed to reduce exposure by 96% and reduce the surface contamination of the respirator by 97%.
However, when a smaller cough aerosol is being used (VMD = 3.4 μm), the face shield became less effective and it blocks only 68% of the cough and 76% of the surface contamination.
You may wonder, how does this relates to the Covid-19 virus. In a study conducted by Lee Byung Uk in 2020, it is found that the Covid-19 virus can be found in a respiratory particle of 4.7 μm. Hence, even with a smaller VMD, wearing a face shield would still be able to reduce surface contamination by quite a large percentage.
Meanwhile, the experiment by Lindsley et al. also took into account the distance variable, where they had proved that physical distancing can help reduce exposure to particle.
Nonetheless, the face shields were proven to be useful for workers caring for patients with respiratory infections but they are not a substitute for respiratory protection (face masks) when needed.
What do you think about this? Share your thoughts!